[PATCH] D40622: XOR the frame pointer with the stack cookie when protecting the stack

[Hans Wennborg via Phabricator via llvm-commits]

hans added inline comments.


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Comment at: llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp:2136
+  const TargetRegisterInfo *TRI = DAG.getSubtarget().getRegisterInfo();
+  unsigned FrameReg = TRI->getFrameRegister(MF);
+  MVT PtrVT = TLI.getPointerTy(DAG.getDataLayout(), 0);
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Is there some way we could assert the register we use here stays the same from entry to exit? This is the only part that sounds potentially scary, the rest looks pretty straight-forward.


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Comment at: llvm/lib/Target/X86/X86ISelLowering.cpp:1692
+  // Currently only MSVC CRTs XOR the frame pointer into the stack guard value.
+  return Subtarget.getTargetTriple().isOSMSVCRT();
+}
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It doesn't really matter what the CRT does though, right? I mean, we could do this for non-MSVC targets too, it's just that it's not common practice?


https://reviews.llvm.org/D40622